The stock is getting smashed in after-hours trading, falling more than 10% to about $16.

Now, this sounds totally horrible, and it is in fact bad, but it's not a disaster.

The restatement does not affect cash flow, and the company is sticking with its outlook for the first quarter.

According to the company, what happened is this:

Groupon launched a bunch of new, higher-priced products late last year. At least in the fourth quarter, the return rate on these products was considerably higher than the return rate for Groupon's cheaper offerings.

When customers demand refunds within 60 days, Groupon's accounting treats the refund as a "contra-revenue" event, meaning that it reduces Groupon's revenue and earnings. After 60 days, refunds are treated as an expense, so they only hit earnings.

Going forward, Groupon will use higher refund assumptions for its higher-priced products. So this shouldn't happen again.

And the good news is that the company is not reducing its guidance for the first quarter (which is basically complete) despite using more aggressive refund assumptions.

So this isn't as big a deal as it seems.

But it does mean that Groupon customers aren't as nuts about high-ticket products as Groupon thought they would be, which is not good news for future growth.